Heavy metals in road dust from Xiandao District, Changsha City, China: characteristics, health risk assessment, and integrated source identification

The physicochemical properties and the contents of metals (Cu, Zn, Pb, Cd, Cr, and Fe) in 51 road dust samples from Xiandao District (XDD) were investigated. Enrichment factor (EF), multivariate statistics, geostatistics, and health risk assessment model were adopted to study the spatial pollution pattern and to identify the priority pollutants and regions of concern and sources of studied metals. The mean EFs revealed the following order: Cd > Zn approximate to Pb approximate to Cu > Cr. For non-carcinogenic effects, the exposure pathway which resulted in the highest levels of exposure risk for children and adults was ingestion, followed by dermal contact and inhalation. Hazard index (HI) values for the studied metals at each site were within the safe level of 1 except maximum HICr (1.08) for children. The carcinogenic risk (CR) for Cd and Cr at each site was within the acceptable risk level (1E-06) except CRCr (1.08E-06) for children in the road intersection between the Changchang highway and the Yuelin highway. Cr was identified as the priority pollutant followed by Pb and Cd with consideration of the local population distribution. Spatially, northwest and northeast of XDD were regarded as the priority regions of concern. Results based on the proposed integrated source identification method indicated that Pb was probably sourced from traffic-related sources, Cd was associated with the dust organic material mainly originated from industrial sources, and Cr was mainly derived from both sources.